JP2000102936A - Hollow cylindrical molding having expansion part and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow molding which does not need a complex mold structure such as a cavity insert mold, is molded easily, and has an expansion part with a relatively large expansion ratio at the end part, and a method for producting the molding. SOLUTION: A hollow cylindrical molding 10 is formed by centrifugal molding, and at least one end of the obtained molding 10 is expanded. As a means for expansion, with the end part of the molding 10 heated at the heat distortion temperature of the resin of the molding 10 or above, an expansion jig 30 is inserted into the opening 32 in the end part of the molding 10. Since the molding formed by centrifugal molding is expanded, the expansion ratio can be increased as compared with convention one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow cylindrical molded body having an enlarged diameter portion and a method of manufacturing the same, and more particularly, to a method of manufacturing a pipe with a joint portion and a joint product very easily. And a molded article obtained by the production method.

[0002]

2. Description of the Related Art Corrugated polyethylene pipes (corrugated pipes) are used, for example, as protective pipes for cables buried underground, and the joints are of a type in which a plate-shaped product is wound around a joint and tightened. Is common. However, recently, from the viewpoints of workability and water tightness, plug-in type joints have been proposed.

[0003] It is necessary to provide a taper at the insertion opening of such a joint so that the diameter decreases from the entrance toward the back.

[0004] As disclosed in Japanese Patent Application Laid-Open No. 6-213487, an electrofusion pipe joint has been developed as a joint for joining polyolefin pipes. Even in this electrofusion pipe joint, in order to facilitate the insertion of the pipes, the insertion port of the joint may be provided with a taper so that the diameter decreases from the entrance to the back.

[0005]

In the case where a joint having an insertion port provided with a tapered portion is formed of a synthetic resin, a casting method is generally used. In order to integrally form the tapered portion, a complicated mold such as a slide type insert is required.

It is easy to increase the diameter of a pipe made of a synthetic resin by heating the end of the pipe after the pipe is formed, but it is easy for a pipe made of a thermoplastic resin.
In a pipe made of a thermosetting resin, the diameter expansion of about 5% of the outer diameter is a limit. Therefore, even if the end of a pipe made of a thermosetting resin is expanded to form a tapered joint, it is difficult to insert a pipe having the same outer diameter as the pipe into the tapered joint. there were.

The present invention has been made in view of such a situation, and does not require a complicated mold structure such as a nesting mold, is easy to mold, and has a large-diameter enlarged portion at the end. An object of the present invention is to provide a hollow molded article having the same and a method for producing the same.

[0008]

In order to achieve the above-mentioned object, according to the present invention, there is provided a hollow cylindrical molded body having an enlarged diameter portion, wherein at least one end of a hollow cylindrical molded body formed by centrifugal molding is expanded. It is characterized by comprising. In the present invention, the “hollow cylindrical molded body” is not limited to a hollow pipe having a simple circular cross section, but means a hollow cylindrical molded body having any cross-sectional shape such as a rectangular cross section, a polygonal cross section, or an elliptical cross section. .

It is preferable that the hollow cylindrical molded body is a reactive polymer molded body obtained by reacting and polymerizing a reaction stock solution in a mold while rotating the mold. The reactive polymer molded article is preferably a thermosetting resin, particularly a reactive polymer of a norbornene-based monomer described below.

[0010] The method for producing a hollow cylindrical molded article having an enlarged diameter portion according to the present invention comprises: a step of centrifugally molding the hollow cylindrical molded article;
Expanding the diameter of at least one end of the hollow cylindrical molded body obtained by centrifugal molding.

The means for expanding the diameter is not particularly limited, but the jig for expanding the diameter of the molded body is heated while the end of the molded body is heated to a temperature not lower than the thermal deformation temperature of the resin constituting the molded body. What is necessary is just to insert in an opening part. It is sufficient that the temperature of the diameter-expanding jig is not lower than the thermal deformation temperature of the molded body without heating the end of the molded body. The diameter expanding jig is not particularly limited, but is preferably a tapered jig.

[0012] In the step of centrifugally molding the hollow cylindrical molded body, it is preferable that the reaction stock solution in the mold is reacted and polymerized while rotating the mold.

The rotational angular velocity ω of the mold at the time of centrifugal molding is 1.01 times the reference rotational angular velocity ω ₀ obtained by the following equation (1) obtained by modifying the Phillips stability condition for an inviscid fluid. 2.0 times, preferably 1.03 to 1.07 times, more preferably 1.05 times
It is preferably about twice. In such a range, while rotating the mold, by reacting the undiluted solution in the mold and polymerizing, it is possible to obtain a molded body having a smooth inner peripheral surface without undulation, according to the present inventors. Have been found.

[0014]

Ω ₀ = {3 g / (R−b)} ^1/2 (1) where g is the gravitational acceleration, R is the inner diameter of the mold cavity,
b is the average radial thickness of the reaction solution present in the mold.

In the present invention, the acceleration applied to the reaction stock solution in the mold is not particularly limited, but is preferably 1 G or more and 5 G or less, more preferably 1 G or more and 4 G or less, and particularly preferably 1.2 or more and 4 G or less.

Although the mold is not particularly limited,
For example, a mold made of a non-adhesive material for the molded body obtained by the molding method can be used.

Undiluted reaction solution The undiluted reaction solution is not particularly limited.
Examples include urea-based, nylon-based, epoxy-based, unsaturated polyester-based, phenol-based, and norbornene-based ones, with the norbornene-based being particularly preferred. The temperature of the unreacted solution before entering the mold is preferably 20 to 80 ° C, and the viscosity of the unreacted solution is, for example, 30 ° C,
It is preferably about 20 cps to 1000 cps, and more preferably about 30 cps to 700 cps. If the viscosity of the reaction solution is too low, the reaction solution tends to stay at the bottom without centrifugal force acting.If the viscosity is too high, it is difficult to form a free form using acceleration. There is a tendency.

In such molding, a reinforcing material (molded body) can be manufactured by placing a reinforcing material in a mold in advance and supplying a reaction liquid therein to polymerize.

Examples of the reinforcing material include glass fiber, aramid fiber, carbon fiber, ultra high molecular weight polyethylene fiber, metal fiber, polypropylene fiber, aluminum coated glass fiber, cotton, acrylic fiber, boron fiber, silicon carbide fiber, and alumina fiber. And the like. These reinforcing materials can be used in various shapes, such as those obtained by forming a long fiber or chopped strand into a mat, woven into a cloth, or remaining in a chopped shape. It is preferable that the surface of these reinforcing materials is treated with a coupling agent such as a silane coupling agent in order to improve the adhesion to the resin. The amount to be used is not particularly limited, but is usually 10% by weight or more, preferably 20 to 60% by weight of the total weight of the molded article.

Also, various additives such as an antioxidant, a filler, a pigment, a colorant, a foaming agent, a flame retardant, a sliding agent, an elastomer, a dicyclopentadiene-based thermopolymerized resin and a hydrogenated product thereof are blended. Thereby, the properties of the obtained polymer can be modified.

As the antioxidant, there are various antioxidants for plastics / rubbers such as phenol type, phosphorus type and amine type. Fillers include inorganic fillers such as milled glass, carbon black, talc, calcium carbonate, aluminum hydroxide, mica, potassium titanate, calcium sulfate, and the like. Examples of the elastomer include natural rubber, polybutadiene, polyisoprene, styrene-butadiene copolymer (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and ethylene- Examples include propylene-diene terpolymer (EPDM), ethylene vinyl acetate copolymer (EVA) and hydrides thereof. The additive is usually mixed in advance with one or both of the reaction solutions.

Mold In the present invention, after the undiluted reaction solution is put into the mold, centrifugal acceleration can be applied to the undiluted reaction solution inside the mold. For example, a mold is rotatable around one axis or multiple axes. By rotating the mold, an acceleration due to centrifugal force acts on the reaction solution inside the mold.

The temperature of the mold is preferably between 10 and 150
° C, more preferably 20 to 120 ° C, still more preferably 30 to 100 ° C. Before injecting the unreacted solution into the mold, warm air is circulated inside the mold, and at least the inside of the cavity of the mold is heated to a predetermined temperature. The molding may be performed by pouring the unreacted solution into the cavity.

The material of the mold used in the present invention is as follows.
Although not particularly limited, a material having good adhesiveness to the mold and a material that is non-adhesive to the molded body is preferable in order to obtain a molded body having a smooth outer peripheral surface, for example, cast iron,
Metals such as iron, stainless steel, aluminum and nickel electroformed are preferred. However, in the present invention, a synthetic resin or another material may be used without necessarily using a material that does not adhere to the molded body. Reactive polymerization molding can be performed at a relatively low pressure, and it is not necessary to use a highly rigid mold.

When the mold which is not adhered to the molded body is made of a synthetic resin, a polar resin such as fiber reinforced plastic (FRP), phenol or polyester can be used as the synthetic resin. Since such a mold is not integrated with the reactive polymer molding, the mold apparatus can be removed and used repeatedly for each reactive polymerization molding.

The mold is preferably a split mold that can be formed into a free shape. However, in the case of molding a pipe-shaped molded article such as a pipe having no ribs or the like formed on the outer peripheral surface. Alternatively, a cylindrical mold that is not divided may be used. In the case of a cylindrical mold, since it is necessary to pull out the obtained molded body, in order to improve the releasability, along the inner peripheral surface of the mold,
It is also preferable to apply a wax, a lubricant or the like before injecting the undiluted solution. Further, when the molded body is pulled out, it is possible to start drawing out the molded body after the temperature of the molded body reaches a temperature equal to or lower than the glass transition temperature (Tg) of the molded body, preferably equal to or lower than (Tg-50) ° C. preferable. This is because the shape of the molded body does not collapse and the workability is good.

The polymerization time may be appropriately selected, but when centrifugal force is applied after the completion of the injection of the reaction solution, it takes several seconds to several tens of seconds to raise the mold to a predetermined rotation speed. Is 5 to 30 seconds, more preferably 5 to 15 seconds.
Seconds.

[0028]

In the manufacturing method according to the present invention, the hollow cylindrical molded body before the enlarged diameter portion is formed is first formed by centrifugal molding. In centrifugal molding, molding is performed in a state where acceleration due to centrifugal force is applied to a stock solution in a mold. Therefore, a prestress is applied radially outward to the obtained hollow cylindrical molded body, and the range in which the diameter can be expanded is wider than that of the hollow cylindrical molded body obtained by a normal casting method.

For example, in the case of a hollow cylindrical molded body made of a thermosetting resin obtained by a conventional casting method, the outer diameter (or inner diameter)
The diameter expansion ratio of the hollow cylindrical molded body made of the thermosetting resin obtained by centrifugal molding according to the present invention can be up to about 9% or more, whereas the diameter expansion ratio of the material is limited to about 5%. It is.
Therefore, at the end of the hollow cylindrical molded body of the present invention, it is possible to form an enlarged diameter portion having a good tapered portion,
The degree of freedom of the shape of the enlarged diameter portion is increased. Further, since the inner diameter of the enlarged diameter portion formed at the end of the hollow cylindrical molded body obtained by the method of the present invention can be increased, the outer diameter of the hollow cylindrical molded body formed with the enlarged diameter portion is increased. It is also possible to connect a hollow cylindrical molded body having the same outer diameter as that of the enlarged diameter portion.

The hollow cylindrical molded body according to the present invention can be used as a joint itself having enlarged diameter portions at both ends, but can also be used as a pipe integrally formed with a joint composed of enlarged diameter portions.

Further, if the method according to the present invention is used, it is of course possible to form a hollow cylindrical molded article having a small diameter.
For example, the outer diameter is 400 mm or more (400 to 4000 m
m, especially 100 to 2500 mm).

Further, by using the method according to the present invention, a hollow cylindrical molded body having a smooth inner peripheral surface without undulation can be formed. In addition, since reactive polymerization is performed in a state where centrifugal acceleration is applied to the reaction stock solution, bubbles are separated from the reaction stock solution by centrifugal force during molding, and voids are eliminated in the obtained molded body.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIGS. 1A and 1B are schematic perspective views of a mold used in a method of manufacturing a hollow cylindrical molded body according to one embodiment of the present invention, and FIG. 1C is an example of the molded body. Schematic perspective view showing,
FIG. 2 is a side view of a driving device for rotating the mold, and FIG.
Is a plan view of the driving device, FIGS. 4A, 4B, and 4C are perspective views showing steps of forming tapered enlarged portions at both ends of the hollow cylindrical molded body, and FIG. It is a schematic sectional drawing which shows the example which used the hollow cylindrical molded object obtained by the method as an electrofusion pipe joint.

In this embodiment, a case will be described in which an electrofusion pipe joint as a hollow cylindrical molded body having an enlarged diameter portion is manufactured. First, the hollow pipe 10 shown in FIG. 1 (C) without the enlarged diameter portion is formed by centrifugal molding. In the centrifugal molding of the present embodiment, the rotational angular velocity ω of the mold is set to the reference rotational angular velocity ω derived from the following equation.
While the mold is being rotated, the reaction stock solution in the mold is reacted and polymerized so as to be in the range of 1.01 to 2.0 times ₀ .

[0036]

Ω ₀ = {3 g / (R−b)} ^1/2 (1) where g is the gravitational acceleration, R is the inner diameter of the mold cavity,
b is the average radial thickness of the reaction solution present in the mold.

The average thickness b in the radial direction of the reaction stock solution is given by b = V _f /, assuming that the inside of the cavity of the mold is a cylindrical surface.
(2πRλ). Here, _Vf is the volume of the reaction solution put into the mold, and λ is the axial length of the cavity of the mold.

In this embodiment, the mold 2 shown in FIGS. 1A and 1B is used to rotate the mold at a rotational angular velocity in the above range.

The mold 2 is axially attached to the outer periphery of both ends thereof in a state in which the mold 4 can be divided into two in the vertical direction along the dividing surface 3 and the molds 4 are combined. And a pair of rolling rings 8. The split mold 4 is made of, for example, an aluminum casting, and the rolling ring 8 is made of cast iron.

The split surface 3 of the split mold 4 is preferably provided with the following sealing material. By installing the sealant, it is possible to prevent inconvenience such as leakage of the undiluted reaction solution from the split surface 3.

That is, the sealing material suitable for the present embodiment is not particularly limited, and a silicone rubber sealing material or the following sealing material can be used.

The sealing material of the present embodiment is a sealing material containing clay as a main component. Clay, the main component of this sealing material, is an aggregate of hydrated silicate minerals, which shows plasticity when mixed with an appropriate amount of water, shows rigidity when dried, and sinters when baked at high temperatures It is defined as such a substance, and its chemical components mainly consist of silicon, aluminum, magnesium, alkali metals, alkaline earth metals and moisture.

Examples of the filler which can be used together with the clay include mica, silica, calcium carbonate, clay (aluminum silicate), talc, diatomaceous earth and the like.
In the sealing material, as other components, preferably contains a petroleum-based or mineral oil-based softener such as aromatex, naphthene, paraffin, white oil, petrolatum, petroleum sulfonate, or a vegetable oil-based softener. May be contained alone or in combination.

The content of the clay component in the sealing material is preferably 30 to 10 with the whole sealing material being 100% by weight.
0% by weight, more preferably 40 to 80% by weight.
The content of the filler in the sealing material is preferably from 0 to 70% by weight, more preferably from 10 to 50% by weight, based on 100% by weight of the whole sealing material. Further, the content of other components in the sealing material is 100% for the entire sealing material.
The weight percentage is preferably 10 to 40% by weight, more preferably 20 to 30% by weight.

The sealing material is formed, for example, in the form of a string having a circular or elliptical cross section. In use, the sealing material is cut into a predetermined length and mounted in a gap to be sealed. Further, this sealing material can be used in combination with a conventional sponge packing or the like.

An inner peripheral surface is formed inside the split mold 4 combined with the split surface 3, and a reaction stock solution having a predetermined viscosity is pressed against the inner peripheral surface by centrifugal force. I have. End plates 6 and 6 are formed at both ends in the axial direction of the split mold 4 so that the through holes 5 are formed. A nozzle for supplying the undiluted reaction solution is inserted from the through hole 5, so that the undiluted reaction solution can be supplied into the mold 2.

As shown in FIGS. 2 and 3, a pair of flanged drive rollers 12 are engaged with one rolling ring 8 of the mold 2, and a pair of flanged driving rollers 12 are engaged with the other rolling ring 8. The drive roller 14 without the lock is engaged. These drive rollers 12 and 14
And a constant torque inverter motor 18,
They all rotate at substantially the same rotation speed. When these drive rollers 12 and 14 are all rotated at substantially the same rotational speed, the rolling ring 8 engaged with them is also rotated around its axis, and the mold 2 composed of the split dies 4 and 4 is also rotated. At the same time, it rotates around the axis. The driving rollers 12, 1
4. The transmission 16 and the motor 18 are mounted on a base 20. The reason why the one driving roller 12 in the axial direction is provided with a flange is that the flange restricts the axial movement of the rolling ring 8, thereby restricting the axial movement of the mold 2. Drive rollers 12, 14 in both axial directions
May be provided with a flange, but only one of them can sufficiently restrict the axial movement of the mold 2.

Next, a method of forming the hollow pipe 10 by the reactive polymerization molding method using the mold 2 will be described. First, as shown in FIG. 1 (B), the split dies 4 and 4 are combined. Then, as shown in FIG. 1 (A), the rolling rings 8 and 4 are attached to both ends of the combined split dies 4 and 4. 8 is mounted, and the mold 2 is assembled. Next, this mold 2 is
3 is rotatably mounted on the driving rollers 12 and 14 shown in FIG.

Thereafter, reactive polymerization molding is performed. The reactive polymerization molding performed in the present embodiment is a molding using a norbornene-based monomer. Specific examples of the norbornene-based monomer to be used include bicyclics such as norbornene and norbornadiene; dicyclopentadiene (cyclopentadiene dimer). ), Tricyclics such as dihydrodicyclopentadiene; tetracyclics such as tetracyclododecene; pentacyclics such as cyclopentadiene trimers; heptacyclics such as cyclopentadiene tetramers; methyl, ethyl, Substituents such as alkyl such as propyl and butyl, alkenyl such as vinyl, alkylidene such as ethylidene, and aryl such as phenyl, tolyl and naphthyl; and further having polar groups such as ester group, ether group, cyano group and halogen atom. Substitutes are exemplified. These monomers may be used in combination of one or more kinds. It is easy to obtain, excellent in reactivity,
From the viewpoint of excellent heat resistance of the obtained resin molded body, tricyclic,
Tetracyclic or pentacyclic monomers are preferred.

The ring-opening polymer to be formed is preferably of a thermosetting type. For this purpose, among the above norbornene-based monomers, it has two or more reactive double bonds such as cyclopentadiene trimer. Those containing at least a crosslinkable monomer are used. The proportion of the crosslinkable monomer in all the norbornene monomers is preferably from 2 to 30% by weight.

It should be noted that, within a range not to impair the object of the present invention,
Monocyclic cycloolefins such as cyclobutene, cyclopentene, cyclopentadiene, cyclooctene and cyclododecene, which can be ring-opening copolymerized with norbornene monomers,
It may be used as a comonomer.

The metathesis catalyst which can be used in molding using a norbornene-based monomer is a norbornene-based catalyst such as tungsten hexachloride, or an organic ammonium molybdate such as tridodecyl ammonium molybdate or tri (tridecyl) ammonium molybdate. There is no particular limitation as long as it is a known metathesis catalyst as a catalyst for bulk polymerization of monomers, but an organic ammonium molybdate is preferred.

As the activator (co-catalyst), JP-A-58-1983
127728, JP-A-4-226124,
JP-A-58-129003, JP-A-4-1452
There is no particular limitation as long as it is a known activator as disclosed in Japanese Patent No. 47, for example, alkyl aluminum halides such as ethyl aluminum dichloride and diethyl aluminum chloride, organic aluminum compounds such as alkoxyalkyl aluminum halides, and organic tin. And the like.

As preparation for molding, a molding material mainly composed of a norbornene-based monomer, a metathesis catalyst and an activator was mixed with a liquid B composed of a norbornene-based monomer and a metathesis catalyst, and the aforementioned norbornene-based monomer and activator. The liquid is divided into two stable liquids and the liquid A, each of which is placed in a separate tank.

To start molding, control the mixer,
The solution A and the solution B from the tank are mixed, and the mixed solution is used as a reaction stock solution by using a nozzle or the like to form the through-hole 5 of the mold 2.
From the mold 2. The viscosity of the reaction solution supplied into the mold 2 is 50 cps to 10 at 30 ° C.
By rotating the mold 2, the undiluted reaction solution adheres to the inner peripheral surface of the mold 2 in a pipe shape by the centrifugal force.

In the present embodiment, the mold 2 does not necessarily need to be heated, but may be heated using a heating medium or hot air from the viewpoint of facilitating the polymerization reaction.

The rotational angular velocity of the mold 2 is calculated by the above-described equation.
Reference rotation angular velocity ω derived from (1)₀ 1.01 times of
Are set to be in a range of 2.0 times. Mold 2 key
The radius R of the inner peripheral surface of the cavity is 0.3 m,
When the axial length λ is 1.0 m,
The volume Vf of the solution was 1.84 × 10^-2m³Place
In this case, the reference rotational angular velocity ω₀Is about
10.1 rad / sec. Therefore, in that case
Is the rotational angular velocity of the mold, the reference rotational angular velocity ω₀ 1.
10.2 to 20.2r in the range of 01 to 2.0 times
Set to ad / sec.

The initial start-up time required for rotating the mold 2 at a constant rotational angular velocity about its axis is generally about several seconds to about 30 seconds. By the time the required rotational angular velocity has been reached, it can be longer than 30 seconds. After the required rotational angular velocity is reached, the mold is rotated at a constant rotational angular velocity. Since it is sufficient that the reaction stock solution has reached the required rotational angular velocity before the gel time, the mold 2
May be rotated around the axis at a constant rotational angular velocity, and then a reaction solution may be supplied through a through-hole 5 through a nozzle.

By rotating the mold 2 around the axis thereof at a constant rotational angular velocity, the unreacted solution supplied into the mold 2 is formed into a pipe shape on the inner peripheral surface of the mold 2 by centrifugal force. By sticking the state until the end of the bulk polymerization, a pipe-shaped molded body can be obtained.

Then, after the rotation of the mold 2 is stopped and the mold 2 is cooled, the rolling ring 8 is removed from the state shown in FIG. 1A to the state shown in FIG. , Split mold 4,4
Is opened, it is possible to obtain a pipe 10 as shown in FIG. The pipe 10 is formed of a reactive polymer molded product of a norbornene-based monomer that is a thermosetting resin.

In the method according to the present embodiment, by applying a centrifugal force to the reaction stock solution, bubbles are separated from the reaction stock solution by the centrifugal force during molding, and voids are eliminated in the obtained molded product.

The inner peripheral surface of the pipe 10 shown in FIG. 1 (C) obtained by the method of this embodiment is a surface obtained by centrifugal force without touching anything during the forming process. There is no inconvenience such as poor curing of the reaction stock solution, and the inner peripheral surface is smooth. In particular,
By setting the rotational angular velocity of the mold to the rotational angular velocity in the specific range described above, it is possible to form a pipe-shaped molded body having a smooth inner peripheral surface without undulation.

The ends of the pipe 10 obtained by centrifugal molding in this way are then subjected to a diameter expansion process shown in FIGS. 4 (A) and 4 (B). That is, while heating both ends of the pipe 10 to a temperature equal to or higher than the thermal deformation temperature, the tapered end diameter increasing jigs 30 are inserted into both open ends of the pipe 10 to increase the inner diameter of the open ends. As shown in (C), the joint 10a in which the tapered enlarged-diameter end opening 32 is formed is obtained.

The heating temperature of both ends of the pipe 10 is not particularly limited as long as it is higher than the thermal deformation temperature of the resin constituting the pipe 10, and is preferably 100 to 180 ° C., particularly preferably 100 to 120 ° C. . Examples of the heating means include heating with hot air, heat radiation, wrapping electric heater, rubber heater winding, and heating with a hot fluid such as oil. In addition, without directly heating both ends of the pipe 10, the diameter-expanding jigs 30 are sufficiently heated in advance, and each diameter-expanding jig 30 is inserted into both open ends of the pipe 10. The inner diameter of the opening end may be enlarged.

The joint 10a thus obtained is
When used as an electrofusion pipe joint, as shown in FIG. 5, a fusion layer 34 is formed on the inner peripheral surface of the joint 10a. The fusion layer 34 is selected according to the material of the pipes 40 and 42 to be joined. If the materials of the pipes 40 and 42 are polyolefin polymers such as polyethylene, polypropylene and polybutene, it is desirable that the pipes 40 and 42 be made of the same polyolefin polymer as the pipes 40 and 42 from the viewpoint of matching the melting points. However, if fusing is possible,
Different types of thermoplastic polymers can be used.

Examples of the thermoplastic polymer that can be used as the fusion layer 34 include high density polyethylene (PE), medium density PE, low density PE, ultra high molecular weight PE,
Ethylene-propylene copolymer, ethylene butene-1
Copolymer, polypropylene (PP), polybutene-1,
Polypentene-1, poly4-methylpentene-1, ethylene-propylene rubber (EPR), ethylene-propylene diene terpolymer (EPDM), ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene- Olefin polymers mainly composed of olefin monomers such as vinyl chloride copolymers; halogenated vinyl polymers such as polyvinyl chloride (PVC); aromatic vinyl polymers such as polystyrene; chlorinated products of these polymers; styrene And various block copolymers composed of conjugated dienes such as isoprene and butadiene, specifically, SI type, SIS type, SBS type , SI-
Hydrocarbon thermoplastic elastomers such as block copolymers such as SIS type, hydrides thereof, and mixtures thereof; unpolymerized copolymers such as polybutadiene, polyisoprene, styrene-butanediene copolymer, chloroprene rubber and butyl rubber; Vulcanized rubber.

These thermoplastic polymers, thermoplastic elastomers and unvulcanized rubbers can be used by mixing with an olefinene-based polymer or the like at an arbitrary ratio. In view of the above, an olefin-based polymer is preferable, and a polyolefin composed of only an olefin-based monomer is particularly preferable.

The heat generating means included in the fusion layer 34 may be any of those in which a heating wire is embedded in the fusion layer and those in which conductive particles such as carbon black are blended in the fusion layer 34. Although a heating means in which conductive particles are blended in the fusion layer 34 is preferable, even with a heating means in which a heating wire is embedded in the fusion layer 34, the heating wire reciprocates in the longitudinal direction of the joint 10a. Any format can be used.

Examples of the conductive particles blended in the fusion layer 34 include carbon black, graphite particles, metal particles (powder of copper, iron, nickel, etc.), and mixtures thereof. However, Ketjen Black having excellent conductivity is preferable.

The blending amount of these conductive particles may be appropriately selected within a range where uniform heating of the heating element is generated by energization, but is usually 5 to 100% by weight of the thermoplastic resin.
The content is 35% by weight, preferably 10 to 30% by weight.

Generally, the pipe joint 10a is connected to the pipe 4 to be joined.
From the viewpoint of the easiness of inserting each end of the joints 0 and 42 into the joint 10a, it is preferable that the tapered large-diameter end opening 32 is formed at each end of the joint 10a. In the present embodiment, the tapered enlarged-diameter end opening 32 is formed by the above-described method, so that the end of each of the pipes 40 and 42 is easily inserted.

Further, since the pipe joint 10a itself is made of a reactive polymer molded product of a norbornene-type monomer,
It also has shape memory recovery properties, and when the fusion layer 34 is melted,
The inner diameter of the enlarged-diameter end opening 32 of the joint 10a is reduced to the dimension before the expansion, and as a result, the inner surface of the fusion layer 34 is opposed to the pipes 40 and 42 to be joined against thermal expansion during melting. The outer peripheral surface is pressed, and both can be closely bonded.

Since the joint 10a obtained by the method according to the present embodiment is a polymer obtained by utilizing a bulk polymerization reaction of a norbornene-based monomer, mechanical properties such as impact resistance and durability are obtained. Excellent characteristics. Also,
According to the method of the present embodiment, the relatively large-diameter pipe 40
The joint 10a connecting the and 42 can also be formed relatively easily.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

For example, in the above embodiment, the electrofusion pipe joint was formed using the method of the present invention. However, in the method of the present invention, other joints and pipes in which the joint portion is formed integrally are formed. It can also be applied to the case.

[0076]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

Example 1 A mold 2 shown in FIG. 1A was prepared and set on the driving rollers 12 and 14 of the mold rotating device shown in FIGS. The pair of split dies 4, 4 are made of aluminum casting,
The outer diameter of the mold is 0.5 m, the radius R of the cavity of the mold is 0.2 m (the inner radius is 400 mm), and its axial length λ
Was 0.5 m. The inner diameter of the through hole 5 of the end plate 6 formed at each end of the split dies 4 and 4 was 0.15 m.

The split dies 4 and 4 were combined on the split surface 3.
The cut surface 3 has a circular cross-section string shape obtained from Yamanaka Casting Co., Ltd.
A mold seal (trade name) was used. Its mold sea
The outer diameter of the cross section of the screw was 3 mm. Also, its mold
When the composition of the seal was analyzed, SiO 2₂Is 46.
30% by weight, Al₂O₃Is 7.50% by weight, Fe
₂O₃1.13% by weight, CaO 1.50% by weight
%, Mg (OH)₂Is 7.60% by weight, and MgO is 2.
60% by weight, Na₂O is 0.10% by weight, K₂O
0.10% by weight, C is 0.65% by weight, aromatic
12.80% by weight, naphthene 7.45% by weight,
Raffin was 7.63% by weight.

With the split surfaces 3 of the split dies 4 and 4 sealed, the rolling rings 8 and 8 were attached. Rolling ring 8,8
Was made of cast iron, its outer diameter was 700 mm, and its axial thickness was 50 mm.

The rolling rings 8, 8 are connected to the driving rollers 12, 14.
The reaction solution was supplied to the inside of the mold 2 using a nozzle from the axial through hole 5 of the split mold. The preparation of the reaction stock solution was performed as follows. Dicyclopentadiene (DC
P) 85% by weight and 15% by weight of tricyclopentadiene
And a total monomer amount of 10
5 parts by weight of styrene-isoprene-styrene block copolymer (Clayton 1170, manufactured by Shell) and 2 parts by weight of Irganox 1010 (Ciba-Geigy), which is a phenolic antioxidant, based on 0 parts by weight. Was dissolved in two containers, one of which was charged with 4 parts of diethyl aluminum chloride (DEAC) based on the mixed monomers.
0 mmol, n-propanol was added at 44 mmol, and silicon tetrachloride was added at 20 mmol (Solution A). On the other hand, tri (tridecyl) ammonium molybdate was added to the mixed monomer at a concentration of 10 mmol (solution B).

The solution A and the solution B are sent to the mixer by a gear pump so as to have a volume ratio of 1: 1. Then, the solution is supplied from the through hole 5 of the mold 2 to the inside of the mold 2 using a nozzle. did. The temperature of the reaction stock solution was 30 ° C., and its viscosity was 300 cps at 30 ° C.

The volume V _f = 1.8 in the cavity of the mold
The reaction stock solution was supplied in an amount of 4 × 10 ⁻² m ^3. Immediately after the completion of the supply, the drive rollers 12 and 14 were rotated, and the mold 2 was rotated around its axis. In 15 seconds, the rotational angular velocity ω of the mold 2 became 13.8 rad / sec, and the speed was maintained. Since the reference rotational angular velocity ω ₀ derived from the above equation (1) was about 13.1, the actual rotational angular velocity ω of the mold was about 1.05 times ω ₀ . Also, when calculating the acceleration acting on the reaction stock solution,
It was 3.89G.

After maintaining this state for 5 minutes, the rotation was stopped, the mold 2 was taken out, the rolling rings 8, 8 were removed, and the split dies 4, 4 were opened. As shown in FIG. Such a pipe 10 was obtained.

For confirmation, the pipe 10 was cut at a plurality of locations and the cross-sectional state was examined. No void was found. In addition, when the inner peripheral surface of the pipe 10 was observed, it was confirmed that the inner peripheral surface had no defects such as poor curing and was smooth without undulation. Also, when the roundness of the hollow section of the pipe 10 was measured, it was close to the roundness, and it was confirmed that good roundness was obtained.

Next, both ends of the pipe 10 were expanded using a jig 30 shown in FIG. The heating temperature of the pipe at the time of diameter expansion was 105 ° C. It was confirmed that the inner diameter of the opening 32 after the diameter expansion could be expanded to 436 mm. This was a diameter expansion ratio of about 9% of the initial inner diameter of 400 mm.

Comparative Example 1 A pipe having the same dimensions as in Example 1 was molded by reaction injection molding using a mold for normal reaction injection molding instead of centrifugal molding. Diameter expansion was performed under the same conditions, but the diameter expansion rate was limited to 5%.
Attempting to continue the diameter expansion process further resulted in a state where a crack was generated from the end.

[0087]

As described above, according to the present invention, without using a complicated mold structure such as a nest type,
It is possible to obtain a hollow cylindrical molded body made of a thermosetting resin having relatively high productivity and having a relatively large diameter expansion portion at an end thereof.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic perspective views of a mold used in a method of manufacturing a hollow cylindrical molded body according to an embodiment of the present invention, and FIG. 1C is an example of the molded body. FIG.

FIG. 2 is a side view of a driving device for rotating a mold.

FIG. 3 is a plan view of a driving device.

4 (A), 4 (B), and 4 (C) are perspective views showing steps of forming tapered enlarged portions at both ends of a hollow cylindrical molded body.

FIG. 5 is a schematic sectional view showing an example in which a hollow cylindrical molded body obtained by the method of the present invention is used as an electrofusion pipe joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Die 3 ... Split surface 4 ... Split die 8 ... Rolling ring 10 ... Pipe (hollow cylindrical molded body) 10a ... Joint 12, 14 ... Drive roll 30 ... Large diameter jig 32 ... Large diameter end opening 34 ... fusion layer 40, 42 ... pipe to be joined

Continued on the front page F-term (reference) 4F205 AA12 AA46 AC05 AG08 AG23 AH11 GA01 GB01 GC04 GF01 GN01 GN08 GN13 GN28 GW06 GW26 4F213 AA12 AA46 AC05 AG08 AG23 AH11 WA03 WA11 WA36 WA54 WA72 WB01 WC02 WC01

Claims (4)

[Claims] 1. A hollow cylindrical molded article having an enlarged diameter portion formed by enlarging at least one end of a hollow cylindrical molded article formed by centrifugal molding. 2. The hollow cylinder according to claim 1, wherein the hollow cylindrical molded body is a reactive polymer molded body obtained by reacting and polymerizing a reaction solution in the mold while rotating the mold. Shaped body. 3. A hollow cylindrical molded body having an enlarged diameter portion having a step of centrifugally molding a hollow cylindrical molded body, and a step of expanding at least one end of the hollow cylindrical molded body obtained by centrifugal molding. Manufacturing method. 4. The enlarged diameter portion according to claim 3, wherein, in the step of centrifugally molding the hollow cylindrical molded body, the reaction stock solution in the mold is reacted and polymerized while rotating the mold. A method for producing a hollow cylindrical molded article having: